The present invention relates to a method and a device for monitoring the functions of a sensor.
A method and a device for monitoring the functions of a sensor, in particular of a sensor for detecting a measurable value in a motor vehicle, are described in German Unexamined Patent Application No. DE 34 28 879 (corresponding to U.S. Pat. No. 4,730,264). The German application describes a method for continually comparing newly detected measured values with an older stored extreme value. If the new measured value is greater than the extreme value, then the measured value is stored as a new extreme value.
In the automatic feedback control of internal combustion engines, sensors, which function inductively or potentiometrically, and which are connected to a control unit, are often used to detect measurable quantities. Such measurable quantities include, for example, the position of the throttle valve of an Otto (i.e., spark ignition) engine, the position of the control rod of a diesel injection pump, or the position of an accelerator pedal.
During the operational life of a device being monitored, drift effects, due to mechanical wear of the control unit (including any associated limit stops) or contact resistance in the connecting lines leading to the control unit, for example, can corrupt the measured values. Reducing the influences of such effects often entails costly construction or regular servicing and adjustment of such sensors.
The object of the present invention, given a method for monitoring the functions of a sensor, is to detect and, if necessary, to compensate for, occurring drift effects.